Right ventricular failure is the most important predictor of mortality for patients with severe pulmonary arterial hypertension (PAH). Based on the preliminary data of Projects 1, 2, and 3, patients with scleroderma-associated PAH-(SSc) have a significantly higher rate of right ventricular failure for the same levels of pulmonary artery pressures as patients with IPAH. Since the overall goal of our SCCOR is to understand the molecular mechanisms of right ventricular failure, increase the accuracy of phenotyping of patients, with severe PAH and to test novel therapies, an imaging core is central for several of the goals of this proposal. The primary functions of the Imaging Core are to provide comprehensive analysis and interpretation of multiple imaging biomarkers, and to develop and test novel imaging biomarkers. These imaging parameters will serve to (a) characterize extent and progression of right ventricular disease associated with PAH (with Projects 1,2, 3);(b) phenotype cardiovascular function to facilitate interpretation of serologic and proteomic markers in PAH (with Cores C, D and F and Projects 1, 2 and 3), and (c) develop/ test/ evaluate novel imaging biomarkers in terms of their sensitivity and their predictive potential for disease characterization (with Projects 1,2 and 3). Therefore, the Imaging Core will be involved actively in phenotype characterization, and biomarker discovery and validation. The right ventricle is negatively impacted by pulmonary disease, and deterioration in global RV structure and function have been measured previously using echocardiography, magnetic resonance imaging (MRI) and multi-detector CT (MDCT). The overall strategy of the imaging core will be to (1) provide reliable measurements of echocardiographic derived cardiac function, (2) provide reliable measurements of MRI and MDCT derived cardiac and pulmonary vascular function, and (3) implement novel imaging methods designed to measure regional myocardial dysfunction and myocardial fibrosis/ inflammation. Overall, we aim to comprehensively characterize RV status by assessing RV global function, RV regional function, pulmonary distensibility and RV fibrosis using noninvasive imaging methods.